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Study: Dark Chocolate May Lower Heart Disease and Stroke Risks


5 Star


Study: Dark Chocolate May Lower Heart Disease and Stroke Risks

Our Review Summary

We remind journalists and consumers that you should always read our commentary rather than simply glancing at the grade or star score given a story – because this is an example of a story that addressed most of our criteria yet – in our opinion – failed readers.

The opening line is unacceptable in our view:

“Should people at high risk of heart attack and stroke eat dark chocolate every day?

Maybe, according to a new study from Australia.”

Later, one independent expert calls it “wonderful news” while another says it over-assumes benefits, is based on intermediate risk factors and ignores dangers.

Which is it?

Journalism should help readers hone their critical thinking and help them weigh the evidence.

The beginning and ending of this story was more like cheerleading.


Why This Matters

We fear that this is the kind of story that leaves the American public numb to the kind of research news that they should care about.  That’s why this matters.


Does the story adequately discuss the costs of the intervention?


The study included a cost-effectiveness analysis and the story reported on it.  Unfortunately, it didn’t offer any critical analysis of that cost-effectiveness projection.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?


On the one hand, the story dutifully reported what the researchers reported about projected benefits.

But on the other hand, the input of the Harvard nutritionist/epidemiologist raised important questions about over-assumption of benefits, and relying on intermediate risk factors (not actual heart disease events like heart attacks).

So we’ll give it the benefit of the doubt.

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

The story quoted the Harvard expert:

“The researchers are ignoring some downsides, he says. “They are ignoring the dangers of too many calories and too much fat and sugar from the chocolate bar,” he says.”

But somewhere in this review, we must criticize the story for never offering any detailed analysis of the researcher’s “model.” We could do it in the Evidence criterion, but we’ll choose to do it here.

Surprisingly the model used by these researchers did not account for the adverse effects (weight gain, etc) that might accrue from adding a daily 100 g chocolate bar, which might contain as much as 600 calories (!), to your diet for 10 years.  Since the entire underpinning of the story was the validity of the model, this is a weakness in the story.

Does the story seem to grasp the quality of the evidence?


Caveats were raised by both researchers quoted who were not part of the study:

  • One questioning over-assumption of benefits and reliance on intermediate risk factors
  • The other saying “It’s all theoretical based on statistics.”

Does the story commit disease-mongering?


No disease-mongering of heart attack and stroke.

Does the story use independent sources and identify conflicts of interest?


The Harvard nutritionist/epidemiologist provided vital perspectives.


Does the story compare the new approach with existing alternatives?


At least the story quoted the Harvard expert:

Those at risk of heart attack and stroke should first focus on lifestyle, Ding says. That includes weight loss if needed, exercising regularly, and not smoking.

Does the story establish the availability of the treatment/test/product/procedure?

Not Applicable

The availability of dark chocolate is not in question.

Does the story establish the true novelty of the approach?


The story explained that the study was an evaluation of “studies already published” and that the researcher believed “theirs is the first study to model the long-term effects of eating dark chocolate in reducing cardiovascular risk.”

Does the story appear to rely solely or largely on a news release?


It’s clear that the story did not rely solely on a news release.

Total Score: 8 of 9 Satisfactory

Comments (1)

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Ileana Balcu

June 1, 2012 at 12:58 pm

Great points! Thank you! Oh, no, not another piece of news about how chocolate is healthy! Maybe add another criteria: Was this horse beaten to death yet? ;)